JP4233559B2 - Numerically controlled machine tool - Google Patents

Description

  The present invention relates to a numerically controlled machine tool that prevents a tool or the like from interfering with other members such as a jig to damage a component.

In a numerically controlled machine tool controlled by a numerical control device, when a tool and jig collide due to a mistake in a machining program or a tool offset setting, etc., and a weak component such as a tool or spindle is damaged. There is.
FIG. 3 is a diagram showing an example of this collision. The tool 1 is attached to the main shaft and moves in the Z-axis direction (vertical direction in FIG. 3). A workpiece is attached to the table 3 by a jig 2, and the table 3 is driven in the X and Y axis directions orthogonal to the Z axis direction and orthogonal to each other, and the workpiece is processed by the tool 2. The However, the tool 1 and the jig 2 may collide and damage the tool, the spindle, or the like for some reason such as a machining program error or a tool offset amount (tool length or tool diameter correction amount) setting error.

  In a numerically controlled machine tool equipped with an abnormal load detection function, the machine can be stopped by the abnormal load detected by this abnormal load detection function. However, this abnormal load detection function detects an abnormal load during high-speed movement. However, when the machine is stopped, weak components such as tools are already damaged, and the abnormal load detection function can cause collision and interference between the tool and other objects during high-speed movement. It is difficult to prevent machine damage by the method of detecting the occurrence.

  Therefore, in Patent Document 1, in order to prevent machine damage due to a mistake in a machining program, a setting error in a tool offset amount, or the like, the rapid feed speed at the time of the trial cutting process can be protected to a portion that is vulnerable to mechanical component impact. Trial machining at low speed, then in continuous operation mode, safe fast feed faster than the fast feed speed during the trial cutting process, so long as there is no damage to machine parts even if tools and workpieces interfere with each other When machining is completed without any human intervention during machining in this continuous operation mode, the first one is first processed based on the machining conditions (machining program, correction amount data) at this time. The invention has been proposed in which machining is performed at the safe rapid feed rate, and then continuous machining is performed at the rapid machining rate.

  Further, in Patent Document 2, when converted to the manual operation mode, the parameters of the set manual mode 1 or mode 2 are read and the manual operation is performed. It is described that the time constant during deceleration and the rapid traverse rate are limited to 50% or 30% in normal automatic operation.

  Further, in Patent Document 3, when the entire NC program is specified during the test operation, the maximum speed of the feed axis and the maximum feed speed of the cutting feed speed are rewritten to the respective clamp speeds. In the specified range, an invention is described in which the program is executed by rewriting the maximum speeds of the rapid feed speed and cutting feed speed of the feed shaft to the respective clamp speeds.

JP-A-11-33867 JP-A-4-82645 JP 11-165238 A

  When high-speed machining is performed by a numerically controlled machine tool, when a tool and jig collide due to a mistake in the machining program, etc., if this collision is detected by the abnormal load detection function of the numerically controlled machine tool, the machine is already damaged. Since there are many cases in which this occurs, interference between the tool and other objects such as a jig occurs during manual operation in advance as described in Patent Documents 1 to 3 described above. The method of detecting and confirming whether or not to take is taken.

Normally, whether or not this interference occurs is confirmed by executing the machining program for each block and checking whether or not the interference occurs. That is, single block operation is performed, the cycle start button is operated, only one block is executed and stopped, and if no interference occurs, the cycle start button is operated again to execute one block.
In this case, even if one block is executed, if the feed axis is moved at a high rapid feed speed, the machine may be damaged when interference occurs. Therefore, as shown in Patent Documents 1 to 3, the rapid traverse speed commanded by the program is switched to a low speed, single block operation is performed, and it is confirmed whether collision or interference has occurred. Can be prevented.

However, since the fast-forwarding speed is switched to a low speed and executed one block at a time to check whether interference occurs, there is a problem that this confirmation work takes time and is not efficient. In the inventions described in Patent Documents 1 to 3 described above, when confirming a program by manual operation or test operation, etc., since the fast-forwarding speed is switched to a low speed, the confirmation operation takes time. But not efficient.
SUMMARY OF THE INVENTION An object of the present invention is to provide a numerically controlled machine tool capable of efficiently executing a program confirmation check as to whether or not a collision between a tool and another object such as a jig or interference occurs.

The present invention provides a numerical control machine tool for driving a drive motor for each axis based on a machining program, a selection means for selecting a machining program confirmation mode for confirming the operation of the machining program, and a single block in the machining program confirmation mode. Monitoring means for monitoring a cycle start signal for executing a machining program for each block by operation, and when the cycle start signal is detected by the monitoring means, a rapid feed speed is set in advance for a rapid feed command for each axis. A means for changing to a lower speed than the value and executing the command of the block
By providing a feed speed change command means composed of an override command means for changing the feed speed during the single block operation in the machining program confirmation mode, collision and interference between the tool and other objects can be efficiently performed, and It was made possible to detect safely and reliably.

  In machining program confirmation mode, the command is executed at a low speed rapid feed for each block by single block operation, and if there is no problem after confirmation by the operator, the fast feed speed can be increased and executed. Confirmation can be performed. Even if the fast feed speed is increased, the next block is executed at a low speed, so that the next block command is not erroneously executed at a high speed.

  FIG. 1 is a principal block diagram of a numerical controller 10 for controlling a numerically controlled machine tool according to an embodiment of the present invention. The CPU 11 is a processor that controls the numerical controller 10 as a whole. The CPU 11 reads out a system program stored in the ROM 12 via the bus 19 and controls the entire numerical control device according to the system program. The RAM 13 is input by an operator via a display / manual input means unit 20 comprising temporary calculation data, display data, a display composed of CRT, liquid crystal, etc. and manual input means composed of a keyboard or the like. Various data are stored. The CMOS memory 14 is configured as a non-volatile memory that is backed up by a battery (not shown) and that retains the storage state even when the power of the numerical controller 10 is turned off. In the CMOS memory 14, a machining program read via the interface 15, a machining program input via the display / manual input means unit 20, and the like are stored. The ROM 12 stores in advance a program in the program confirmation mode that is a feature of the present embodiment.

The interface 15 enables connection between the numerical controller 10 and an external device. The PMC (programmable machine controller) 16 is a sequence program built in the numerical controller 10, and attaches the I / O unit 17 to an auxiliary device of a machine tool to be controlled (for example, an actuator such as a robot hand for tool change). Through which signals are output and controlled. In addition, it receives signals from various switches on the operation panel provided on the machine tool main body, which is a control object controlled by the numerical control device, performs necessary signal processing, and then passes them to the CPU 11.
The axis control circuits 30 to 32 for the respective feed axes receive the movement command amounts of the respective feed axes from the CPU 11 and output the commands for the respective feed axes to the servo amplifiers 40 to 42. Upon receiving this command, the servo amplifiers 40 to 42 drive the servo motors 50 (for the X axis), 51 (for the Y axis), and 52 (for the Z axis) of each feed axis of the machine (control target). Each feed axis servo motor 50-52 has a built-in position / speed detector. The position / speed feedback signal from the position / speed detector is fed back to the axis control circuits 30-32 for position / speed feedback control. Do. In FIG. 1, the position / speed feedback is omitted.

  The spindle control circuit 60 receives a spindle rotation command and outputs a spindle speed signal to the spindle amplifier 61. The spindle amplifier 61 receives the spindle speed signal, rotates the spindle motor 62 at the commanded rotation speed, and drives the spindle. The position coder 63 feeds back a feedback pulse to the spindle control circuit 60 in synchronization with the rotation of the spindle motor 62 to perform speed control.

  The configuration of the numerical control device 10 described above is almost the same as that of the conventional numerical control device, and the difference is that a program for executing processing in the machining program confirmation mode is stored in the ROM 12. A normal machining program execution mode and a machining program confirmation mode can be selected from the display / manual input means unit 20.

  Therefore, a machining program is created using the display / manual input means unit 20 or the machining program created externally is stored in the CMOS memory 14 read via the interface 15, and then the machining program is first stored. Before executing in the normal mode, the program is executed in the machining program check mode to check whether interference between the tool and another object occurs.

FIG. 2 is a flowchart showing processing in the machining program confirmation mode.
When the numerical control device 10 is designated by the display / manual input means unit 20 and the machining program confirmation mode is selected, the CPU 11 of the numerical control device 10 starts the process shown in FIG.
First, it is determined whether there is a cycle start signal, and waits until the cycle start signal is input (step S1). When the operator operates a cycle start button provided in the display / manual input means unit 20 and inputs a cycle start signal, the CPU 11 reads one block from the beginning of the designated machining program (step S2), It is determined whether the command of the read block is the program end (step S3). If it is not the program end command, it is determined whether it is a fast feed command for the feed axis (step S4). Start (step S5). If the read command is a fast-forward command, the rapid-feed speed of the read-out command of the read block is changed to a predetermined speed (slower than the normal fast-forward speed) lower than the preset upper limit value, The execution of the command is started (step S6).

If the block command is a spindle rotation command, the CPU 11 outputs a spindle speed command to the spindle control circuit 60, drives the spindle motor 62 via the spindle amplifier 61, and based on a feedback signal from the position coder 63. Speed feedback control is performed to control the speed of the spindle to which the tool 1 is attached.
If the command of the block is a movement command to the feed axes of the X, Y, and Z axes, a distributed movement command to each axis is output to the axis control circuits 30 to 32, and this movement command and position / speed detection are performed. Servo motors 50 to 52 that perform feedback control of position and speed based on position and speed feedback signals fed back from the device and drive the feed axes of X, Y, and Z axes via servo amplifiers 40 to 42, respectively. Drive control.

  In addition, the CPU 11 repeatedly determines whether a temporary stop command has been input (step S7), a speed change command has been input (step S8), or whether the command execution has been completed (step S10). The operator monitors the operation of the machine tool, and even when the tool 1 collides with another object such as the jig 2, the fast-forward command is switched to a low speed in step S6. Since it is operating, it is possible to easily detect a collision between the tool 1 and another object such as the jig 2 in advance.

  Since the rapid traverse speed has been switched to low speed, the machine operation will be slow, and when the amount of movement of the rapid traverse command commanded by the program is large, the completion of execution of the rapid traverse command for the relevant block will be delayed and take time. become. Therefore, the operator monitors the operation of the machine, and when it is determined that there is no problem even if the speed is increased, speed change command means such as an override switch provided in the display / manual input means unit 20 is set. By operating, a speed change command is input (step S8), and the speed is increased (step S9).

  On the other hand, the operator monitors the machine operation and operates a temporary stop command button provided on the display / manual input means unit 20 when a collision or interference between the tool and another object is likely to occur. (Step S7), the operation of the machine is temporarily stopped (Step S11). The operator investigates the cause of collision and interference, corrects the mistake if it is a program error, changes to the optimal offset amount or changes the tool if the tool offset amount is set incorrectly, etc. Then, a process for eliminating the cause of the interference is performed, and a restart command is input from the display / manual input means unit 20 (step S12). When this restart command is input, the CPU 11 starts the process that has been temporarily stopped, whether the execution of the block has been completed (step S10), whether the temporary stop command has been input (step S7), or a speed change command. Is repeatedly determined (step S9).

When the execution of the command in the block ends, the process returns to step S1 and waits until a cycle start signal is input. If the operator inputs a cycle start signal, the next one block is read (step S2), and the processing after step S3 described above is executed.
Thereafter, each time the cycle start signal is input, the program is sequentially executed for one block. At this time, if it is a fast feed command, the machine is driven by switching to a predetermined speed lower than the fast feed speed, and the program ends in step S3. This operation process is repeated until the command is read. As a result, as described above, since the fast-forwarding speed is slow, it becomes easy to detect the collision and interference between the tool 1 and another object in advance. If the operator can determine that no collision or interference occurs, the operation is accelerated by increasing the speed, thereby promoting the process. Even if the speed is increased, it is limited to the processing of the command by the block. Even when a fast-forward command is issued in the next block or later, it is switched to a low speed as described above. It is never driven. As a result, the program checking operation can be executed efficiently, safely and reliably.

It is a principal part block diagram of the numerical control apparatus in the numerical control machine tool of one Embodiment of this invention. It is a flowchart of the process in the program confirmation mode in the same embodiment. It is explanatory drawing of a collision with tools and other things, such as a jig | tool, and interference generation in a machine tool.

Explanation of symbols

1 Tool 2 Jig 3 Table 10 Numerical Control Device

Claims (2)

In a numerically controlled machine tool that drives a drive motor for each axis based on a machining program,
Selecting means for selecting a machining program confirmation mode for confirming the operation of the machining program;
Monitoring means for monitoring a cycle start signal for executing a machining program for each block by single block operation during the machining program confirmation mode;
Means for changing the rapid feed speed to a speed lower than a preset upper limit value for a rapid feed command of each axis when a cycle start signal is detected by the monitoring means, and executing the command of the block;
Feed speed change command means for changing the feed speed during single block operation in the machining program confirmation mode;
A numerically controlled machine tool characterized by comprising: The numerically controlled machine tool according to claim 1, wherein the feed speed change command means comprises an override command means for changing the feed speed.

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